Epstein-Barr virus is a ubiquitous human herpesvirus infecting greater than 95% of the adult population and is associated with numerous human cancers. One recent report identified an association between a suppressor of cell migration Nm23-H1 and one of the essential EBV latent antigens, EBNA3C. This was a critical finding as it was the first discovery of a tumor virus antigen been involved in regulation of cell migration. EBNA3C was shown to reverse the inhibitory effects of Nm23-H1 and mediates the translocation of Nm23-H1 to the nucleus. In this proposal we will investigate the association of these molecules in EBV infected cells and further characterize the interaction to determine specific motifs that may be important for interaction of Nm23-H1. We will identify and characterize cellular and viral proteins that associate with Nm23-H1 in complex with EBNA3C as well as other critical EBNA protein including EBNA1. We will also screen for cellular genes that may be regulated by Nm23-H1 using microarray analyses and determine the transcription profiles in the presence and absence of EBNA3C/EBNA1. Specific cellular genes will be selected that are known to be involved in cell migration. We will determine if Nm23-H1 and the EBV EBNA protein can alter the transcriptional activities of these known cellular genes. Further analyses will be completed on the promoters to determine the specific binding sites of these cellular factors through mutagenesis and biochemical analyses that will provide a readout of the effects on transcription and cell migration. Cellular molecules that also associate with Nm23-H1 will also be investigated to determine the functional consequences of the associations. These studies will elucidate a mechanism by which EBV and possible tumor viruses can affect cell migration in infected tumor cells.